Meat, fish, or dairy products yield soils containing lipids such as oils and fats. These soils present special problems in detergent formulation and application, particularly when present on food storage, processing and preparation equipment. Alkali metal hydroxide solutions can degrade fats and oils by saponification reactions and are commonly employed in combination with water-conditioning condensed phosphates such as sodium tripolyphosphates, which also act to disperse or emulsify fatty soils. However, in recent years, the use of high concentrations of phosphate in detergents has come under increasing attack due to environmental concerns, and the permissible phosphate content of cleaning compositions has been severely limited by many states or municipalities, e.g., to no more than 0.5%.
Although water-soluble or dispersible polymers, such as those disclosed in U.S. Pat. No. 3,671,440, have been used to replace phosphate salts as water-conditioners, such polymers have not served as effective phosphate substitutes insofar as fat dispersal is concerned. Also, polyacrylic acids exhibit varying degrees of instability in chlorinated detergents and can substantially degrade the chlorine content of such compositions. Other dispersants such as organic solvents or synthetic surfactants can act to disperse or emulsify fatty oils, but often can exhibit unstability in highly alkaline cleaning systems at effective concentrations or can be toxic.
Therefore a need exists for aqueous highly-alkaline cleaning solutions which will both disperse and degrade deposits of fatty or oily soils on articles such as food-processing equipment or utensils, in the presence of substantial water hardness factors.